Substrate processing method and substrate processing apparatus

Abstract

The invention provides a substrate processing method and a substrate processing apparatus, which can control the etching amount of a nitride film. A substrate processing method according to one embodiment of the present disclosure comprises: a step (a) in which a substrate having a nitride film on the surface thereof is prepared; (b) exposing the substrate to plasma generated from a first processing gas containing hydrogen gas and oxygen gas; (c) supplying a second processing gas containing a fluorine-containing gas and a basic gas to the substrate; a step (d) in which the step (b) and the step (c) are performed a first number of times in the order of the step (b) and the step (c); and a step (e) in which, after the step (d), the substrate is subjected to a heat treatment.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus. BACKGROUND

[0002] Disclosed is a technique in which, after a SiCN film formed on a surface of a substrate is supplied with hydrogen gas and oxygen gas to oxidize a surface layer of the SiCN film and form an oxide film, the oxide film is etched to be removed (for example, refer to Patent Literature 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2023-179001 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The present disclosure provides a technique capable of controlling an etching amount of a nitrided film.

[0008] SOLUTION TO PROBLEM

[0009] A substrate processing method of one embodiment of the present disclosure includes: step (a) preparing a substrate having a nitrided film on a surface; step (b) exposing the substrate to plasma generated from a first processing gas containing hydrogen gas and oxygen gas; step (c) supplying the substrate with a second processing gas containing a fluorine-containing gas and an alkali gas; step (d) performing the step (b) and the step (c) in the order of the step (b), the step (c) for a first number of times; and step (e) performing heat treatment on the substrate after the step (d).

[0010] EFFECT OF THE INVENTION

[0011] According to the present disclosure, it is possible to control an etching amount of a nitrided film. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a flowchart illustrating a substrate processing method according to an embodiment.

[0013] Figure 2 is a vertical cross-sectional view of a substrate processing apparatus according to an embodiment.

[0014] Figure 3 is a horizontal cross-sectional view of a substrate processing apparatus according to an embodiment.

[0015] Figure 4 is a graph illustrating a relationship between a first number of times and an etching amount of a SiCN film.

[0016] Figure 5 This is a graph showing the surface analysis results of the SiO2 film that has not undergone free radical treatment.

[0017] Figure 6 This is a graph showing the surface analysis results of the SiCN film that has not undergone free radical treatment.

[0018] Figure 7 This is a graph showing the surface analysis results of a SiCN film that has undergone free radical treatment.

[0019] Figure 8 This is a graph showing the oxygen concentration on the surface of the SiCN film.

[0020] Figure 9 This is a graph showing the etching amount of the SiCN film. Detailed Implementation

[0021] The non-limiting embodiments illustrated in this disclosure will now be described with reference to the accompanying drawings. Throughout the accompanying drawings, identical or corresponding components or parts are labeled with the same or corresponding reference numerals, and repetitive descriptions are omitted.

[0022] [Substrate processing method]

[0023] Reference Figure 1 The substrate processing method involved in the embodiments will be described below. Figure 1 This is a flowchart illustrating a substrate processing method according to an embodiment. The substrate processing method according to the embodiment includes... Figure 1 Steps S1 to S9 are shown.

[0024] In step S1, a substrate with a nitride film on its surface is prepared. The substrate is, for example, a silicon wafer. The nitride film is, for example, a film containing silicon (Si) and nitrogen (N). Films containing silicon and nitrogen are, for example, SiN films and SiCN films. The nitride film may also contain elements different from silicon and nitrogen. Different elements are, for example, oxygen (O), boron (B), or combinations thereof. The nitride film may also be a film containing boron and nitrogen. A film containing boron and nitrogen is, for example, a BN film.

[0025] In step S2, the substrate prepared in step S1 is subjected to a free radical treatment. The free radical treatment includes exposing the substrate to a plasma generated from a first processing gas containing hydrogen and oxygen. The plasma contains reactive species such as oxygen free radicals. During the free radical treatment, the reactive species act on the surface of the nitride film, thereby oxidizing the surface of the nitride film to form an oxide layer. In step S2, the thickness of the oxide layer formed on the surface of the nitride film can be adjusted by changing the concentration of oxygen contained in the first processing gas. The first processing gas may also contain inactive gases such as argon and nitrogen. Step S2 may also include maintaining the temperature of the substrate at a first temperature. The first temperature is, for example, below 80°C.

[0026] In step S3, purging is performed. Purging may include removing residual gases in the processing space by evacuating the processing space used to process the substrate. Purging may also include removing residual gases in the processing space by supplying inert gases such as argon or nitrogen to the processing space used to process the substrate.

[0027] In step S4, a chemical oxide removal (COR) process is performed. The COR process involves supplying a second processing gas containing a fluorine-containing gas and an alkaline gas to the substrate without generating plasma. In the COR process, the fluorine-containing gas and the alkaline gas react with the oxide layer to modify it, generating ammonium fluorosilicate [(NH4)2SiF6] as a reaction product. The fluorine-containing gas is, for example, hydrogen fluoride (HF). The alkaline gas is, for example, ammonia (NH3). The second processing gas may also contain inert gases such as argon or nitrogen. Step S4 may also include maintaining the substrate temperature at a second temperature. The second temperature is, for example, above 50°C and below 100°C. The second temperature may be the same as the first temperature. In this case, free radical treatment and COR treatment can be performed continuously without temperature changes. Therefore, productivity is improved.

[0028] In step S5, purging is performed. The purging in step S5 can be the same as the purging in step S3.

[0029] In step S6, it is determined whether steps S2 to S5 have been performed for the first number of times in the order of steps S2 to S5. If the number of times performed has not reached the first number (step S6 is "No"), steps S2 to S5 are performed again. If the number of times performed has reached the first number (step S6 is "Yes"), proceed to step S7. Steps S2 to S5 are repeated in this order until the first number of times is reached, thereby adjusting the thickness of the oxide layer formed on the surface of the nitride film. The first number can be once or more than twice.

[0030] In step S7, the temperature of the substrate is raised from the second temperature to a third temperature. The third temperature is a temperature higher than the second temperature. For example, the third temperature is 200°C or higher.

[0031] In step S8, the substrate is heat-treated. The heat treatment includes heat-treating the substrate in an atmosphere of inert gas such as argon or nitrogen while maintaining the substrate temperature at a third temperature. During the heat treatment, ammonium fluorosilicate, as a reaction product, sublimates and is removed from the substrate.

[0032] In step S9, purging is performed. The purging in step S9 can be the same as the purging in step S3. After purging in step S9, the process ends.

[0033] As explained above, according to the substrate processing method of the embodiment, a substrate having a nitride film on its surface is prepared. Then, for the substrate, free radical treatment and COR treatment are performed for the first time in the order of free radical treatment and COR treatment. Next, the substrate is heat-treated. In this case, the thickness of the oxide layer formed on the surface of the nitride film can be adjusted by changing the number of first treatments. Therefore, the etching amount of the nitride film can be controlled.

[0034] In this embodiment, steps S2 to S9 can be performed within the same processing container. In this case, the nitride film can be etched and removed within one processing container. However, some of steps S2 to S9 can also be performed within different processing containers. For example, steps S8 and S9 can also be performed in different processing containers than steps S2 to S6. In this case, step S7 can be omitted.

[0035] The substrate processing method described in the embodiments can also be performed in a processing container that houses multiple substrates in a rack-like manner. In this case, nitride films can be etched onto multiple substrates at once. Therefore, productivity is improved.

[0036] [Substrate processing apparatus]

[0037] Reference Figure 2 and Figure 3 The substrate processing apparatus 100 according to the embodiments will be described below. Figure 2 This is a vertical cross-sectional view showing the substrate processing apparatus 100 according to the embodiment. Figure 3 This is a horizontal cross-sectional view showing the substrate processing apparatus 100 according to the embodiment. (As shown) Figure 2 and Figure 3 As shown, the substrate processing apparatus 100 includes a processing container 1, a gas supply unit 20, a plasma generation unit 30, an exhaust unit 40, a heating unit 50, and a control unit 90.

[0038] The processing container 1 is a vertical cylindrical body with an open bottom and a top. The processing container 1 is made of, for example, quartz. A top plate 2 is provided near the upper end inside the processing container 1, and the area below the top plate 2 is closed. The top plate 2 is also made of, for example, quartz. A metal manifold 3, shaped like a cylinder, is connected to the opening at the lower end of the processing container 1 via a sealing member 4. The sealing member 4 is, for example, an O-ring.

[0039] Manifold 3 supports the lower end of processing container 1. Wafer boat 5 is inserted into processing container 1 from below manifold 3. Wafer boat 5 is used to hold multiple (e.g., 25 to 150) substrates W substantially horizontally in a spaced-apart manner along the vertical direction. Wafer boat 5 is, for example, formed of quartz. Wafer boat 5 has, for example, three pillars 6, through grooves formed in the pillars 6 to support the multiple substrates W.

[0040] The wafer boat 5 is placed on the rotating stage 8 via an insulating cylinder 7. The insulating cylinder 7 is made of, for example, quartz. The insulating cylinder 7 suppresses heat dissipation from the opening at the lower end of the manifold 3. The rotating stage 8 is supported on a rotating shaft 10. The opening at the lower end of the manifold 3 is opened and closed via a cover 9. The cover 9 is made of, for example, a metal material such as stainless steel. The rotating shaft 10 passes through the cover 9.

[0041] A magnetohydrodynamic seal 11 is provided in the through portion of the rotating shaft 10. The magnetohydrodynamic seal 11 hermetically seals the rotating shaft 10 and supports it in a rotatable manner. A sealing member 12 for maintaining the airtightness of the processing container 1 is provided between the periphery of the cover 9 and the lower end of the manifold 3. The sealing member 12 is, for example, an O-ring.

[0042] The rotating shaft 10 is mounted, for example, at the front end of the arm 13 supported by a lifting mechanism such as a wafer boat lift. Lifting is performed via the arm 13, thereby lifting the wafer boat 5, the insulation cylinder 7, the turntable 8, and the cover 9 together with the rotating shaft 10, so as to insert and remove them relative to the processing container 1.

[0043] The gas supply unit 20 supplies various processing gases into the processing container 1. The gas supply unit 20 includes, for example, gas nozzles 21, 22, 23, and 24. Gas nozzles 21, 22, 23, and 24 are, for example, formed of quartz. The gas supply unit 20 may also include other gas nozzles.

[0044] The gas nozzle 21 has an L-shape, extending vertically upwards after passing through the side wall of the manifold 3. The vertical portion of the gas nozzle 21 is disposed within the processing container 1. Multiple gas holes 21a are provided in the vertical portion of the gas nozzle 21. The multiple gas holes 21a are arranged at predetermined intervals along the extending direction of the gas nozzle 21. Each gas hole 21a, for example, faces towards the center CT of the processing container 1.

[0045] A supply path L1 is connected to the gas nozzle 21. Along the supply path L1, from upstream to downstream in the gas flow direction, an oxygen supply source G1, a mass flow controller F1, and an on / off valve V1 are sequentially arranged. The timing of the oxygen supply from the supply source G1 is controlled by the on / off valve V1, and the oxygen supply from the supply source G1 is adjusted to a predetermined flow rate by the mass flow controller F1. Oxygen flows from the supply path L1 into the gas nozzle 21 and is ejected horizontally from multiple gas holes 21a toward the center CT of the processing container 1.

[0046] The gas nozzle 22 has an L-shape, extending vertically upwards after passing through the side wall of the manifold 3. The vertical portion of the gas nozzle 22 is disposed within the processing container 1. A plurality of gas holes 22a are provided in the vertical portion of the gas nozzle 22. The plurality of gas holes 22a are arranged at predetermined intervals along the extending direction of the gas nozzle 22. Each gas hole 22a, for example, faces towards the center CT of the processing container 1.

[0047] A supply path L2 is connected to the gas nozzle 22. Along the supply path L2, a hydrogen fluoride gas supply source G2, a mass flow controller F2, and an on / off valve V2 are sequentially arranged from upstream to downstream in the gas flow direction. Hydrogen fluoride gas is an example of a fluorine-containing gas. The timing of the hydrogen fluoride gas supply from the supply source G2 is controlled by the on / off valve V2, and the flow rate of the hydrogen fluoride gas from the supply source G2 is adjusted to a specified flow rate by the mass flow controller F2. The hydrogen fluoride gas flows from the supply path L2 into the gas nozzle 22 and is ejected horizontally from multiple gas holes 22a toward the center CT of the processing container 1.

[0048] The gas nozzle 23 has an L-shape, extending vertically upwards after passing through the side wall of the manifold 3. The vertical portion of the gas nozzle 23 is disposed in the plasma generation space P. A plurality of gas holes 23a are provided in the vertical portion of the gas nozzle 23. The plurality of gas holes 23a are arranged at predetermined intervals along the extending direction of the gas nozzle 23. Each gas hole 23a is, for example, oriented towards the center CT of the processing container 1.

[0049] A supply path L3 is connected to the gas nozzle 23. Along the supply path L3, a hydrogen supply source G3, a mass flow controller F3, and an on / off valve V3 are sequentially arranged from upstream to downstream in the gas flow direction. The timing of the hydrogen supply from the supply source G3 is controlled by the on / off valve V3, and the flow rate of hydrogen from the supply source G3 is adjusted to a predetermined level by the mass flow controller F3. Hydrogen flows from the supply path L3 into the gas nozzle 23 and is ejected horizontally from multiple gas holes 23a toward the center CT of the processing container 1.

[0050] A supply path L4 is connected to the gas nozzle 23. The supply path L4 can be connected downstream of the on / off valve V3 in the supply path L3. In the supply path L4, an ammonia supply source G4, a mass flow controller F4, and an on / off valve V4 are sequentially arranged from upstream to downstream in the gas flow direction. Ammonia is an example of an alkaline gas. The timing of the ammonia supply from the supply source G4 is controlled by the on / off valve V4, and the ammonia supply from the supply source G4 is adjusted to a specified flow rate by the mass flow controller F4. Ammonia flows from the supply path L4 into the gas nozzle 23 and is ejected horizontally from multiple gas holes 23a toward the center CT of the processing container 1.

[0051] The gas nozzle 24 has a straight tube shape that extends horizontally through the sidewall of the manifold 3. The front end portion of the gas nozzle 24 is disposed inside the processing container 1. The front end portion of the gas nozzle 24 is open.

[0052] A supply path L5 is connected to the gas nozzle 24. Along the supply path L5, from upstream to downstream in the gas flow direction, an argon gas supply source G5, a mass flow controller F5, and an on / off valve V5 are sequentially arranged. Argon is an example of an inert gas. The timing of the argon gas supply from the supply source G5 is controlled by the on / off valve V5, and the argon gas supply from the supply source G5 is adjusted to a specified flow rate by the mass flow controller F5. Argon gas flows from the supply path L5 into the gas nozzle 24 and is ejected from the opening at the front end into the processing container 1.

[0053] A plasma generation unit 30 is disposed on a portion of the side wall of the processing container 1. The plasma generation unit 30 generates plasma from hydrogen and ammonia gas supplied from the gas nozzle 23. The plasma generation unit 30 includes a plasma partition wall 32, a pair of plasma electrodes 33, a power supply line 34, an RF power supply 35, and an insulating protective cover 36.

[0054] The plasma partition wall 32 is hermetically welded to the outer wall of the processing container 1. The plasma partition wall 32 is formed, for example, of quartz. The plasma partition wall 32 has a concave cross-section and covers the opening 31 formed in the side wall of the processing container 1. The opening 31 is formed elongated in the vertical direction in a manner that allows it to cover the entire substrate W supported on the wafer boat 5 in the vertical direction. The plasma partition wall 32 defines a plasma generation space P as an inner space communicating with the interior of the processing container 1.

[0055] A pair of plasma electrodes 33, each having an elongated shape, are disposed facing each other on the outer surface of the plasma dividing wall 32 on both sides. A power supply line 34 is connected to the lower end of each plasma electrode 33.

[0056] The power supply line 34 electrically connects each plasma electrode 33 to the RF power supply 35. For example, one end of the power supply line 34 is connected to the lower end of the side portion of each plasma electrode 33 that serves as the short side, and the other end is connected to the RF power supply 35.

[0057] An RF power supply 35 is electrically connected to the lower end of each plasma electrode 33 via a power supply line 34. The RF power supply 35 supplies, for example, 13.56 MHz of RF power to a pair of plasma electrodes 33. Thus, RF power is applied to the plasma generation space P defined by the plasma dividing wall 32.

[0058] An insulating protective cover 36 is installed on the outside of the plasma partition wall 32, covering it. A refrigerant passage (not shown) is provided on the inner part of the insulating protective cover 36. Cooled refrigerant, such as nitrogen, flows through the refrigerant passage, thereby cooling the plasma electrode 33. Alternatively, a shield (not shown) may be provided between the plasma electrode 33 and the insulating protective cover 36, covering the plasma electrode 33. The shield may be formed of a good conductor, such as metal, and electrically grounded.

[0059] The exhaust section 40 has an exhaust port 41. The exhaust port 41 is located on the side wall of the processing container 1. The exhaust port 41 is positioned opposite to the opening 31. The exhaust port 41 is elongated vertically in relation to the wafer boat 5. A U-shaped cover member 42 is installed on the portion of the processing container 1 corresponding to the exhaust port 41, covering the exhaust port 41. The cover member 42 extends upward along the side wall of the processing container 1. An exhaust pipe 43 is connected to the lower part of the cover member 42. A pressure regulating valve 44 and a vacuum pump 45 are sequentially arranged in the exhaust pipe 43 from upstream to downstream in the gas flow direction. The pressure regulating valve 44 is used to adjust the pressure inside the processing container 1. The vacuum pump 45 is used to discharge the gas inside the processing container 1.

[0060] The heating unit 50 includes a heater 51. The heater 51 has a cylindrical shape that surrounds the processing container 1 radially outward. The heater 51 heats each substrate W housed within the processing container 1 by heating the entire side periphery of the processing container 1.

[0061] The control unit 90 is an electronic circuit such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). The control unit 90 executes various control actions described in this application specification by executing instruction codes stored in memory or by designing circuits for specific applications.

[0062] [Operation of the substrate processing device]

[0063] The operation of the substrate processing apparatus 100 when the substrate processing method according to the embodiment is implemented in the substrate processing apparatus 100 will be described.

[0064] First, the control unit 90 raises the arm 13 to move the wafer boat 5, which holds multiple substrates W, into the processing container 1, and seals the lower opening of the processing container 1 by sealing it with a cover 9. Each substrate W has a nitride film on its surface.

[0065] Next, the control unit 90 controls each part of the substrate processing apparatus 100 to perform steps S2 to S9 in the aforementioned substrate processing method. This removes at least a portion of the nitride film formed on the surface of each substrate W by etching. The control unit 90 adjusts the thickness of the oxide layer formed on the surface of the nitride film by changing the first number in step S6. This allows control over the amount of nitride film etched.

[0066] Next, after pressurizing the processing container 1 to atmospheric pressure and cooling it to the removal temperature, the control unit 90 lowers arm 13 to remove the wafer boat 5 from the processing container 1. This process completes the processing of multiple substrates W.

[0067] 〔experiment〕

[0068] (First Experiment)

[0069] First, a substrate with a SiCN film on its surface was prepared. Next, the prepared substrate was placed in the processing container 1 of the substrate processing apparatus 100, and steps S2 to S9 of the aforementioned substrate processing method were performed within the processing container 1. In step S6, the number of times the first treatment was performed was changed. The number of times the first treatment was 3, 5, or 10. For comparison, steps S3 to S9 were performed without the free radical treatment of step S2. The conditions for the free radical treatment (step S2), the COR treatment (step S4), and the heat treatment (step S8) are as follows.

[0070] (Free radical treatment)

[0071] Substrate temperature: 65℃

[0072] Time: 10 minutes

[0073] RF power: On

[0074] First processing gases: hydrogen + oxygen

[0075] (COR processing)

[0076] Substrate temperature: 65℃

[0077] Time: 1 minute

[0078] RF power: disconnected

[0079] Second processing gas: Hydrogen fluoride gas / ammonia gas = 300 sccm / 300 sccm

[0080] (Heat treatment)

[0081] Substrate temperature: 300℃

[0082] Processing atmosphere: Nitrogen

[0083] Next, the etching amount of the SiCN film was measured. Figure 4 This is a graph showing the relationship between the first etching number and the etching amount of the SiCN film. In Figure 4 In the diagram, the horizontal axis represents the number of times the first etching was performed, and the vertical axis represents the etching depth of the SiCN film in nm. Figure 4 In the diagram, circles indicate results with free radical treatment, while triangles indicate results without free radical treatment.

[0084] like Figure 4 As shown, the SiCN film is hardly etched without radical treatment, whereas it is etched after radical treatment. Based on this result, it is demonstrated that SiCN films can be etched by performing radical treatment prior to COR treatment.

[0085] like Figure 4 As shown, with the free radical treatment performed, the etching amount of the SiCN film increases as the first number increases. Based on this result, it is demonstrated that the etching amount of the SiCN film can be controlled by changing the first number. Specifically, the etching amount of the SiCN film can be increased by increasing the first number.

[0086] (Second Experiment)

[0087] First, a substrate having a SiO2 film on its surface that has not undergone free radical treatment, a substrate having a SiCN film on its surface that has not undergone free radical treatment, and a substrate having a SiCN film on its surface that has undergone free radical treatment were prepared. The substrate having a SiCN film on its surface that has undergone free radical treatment was formed by placing the substrate having the SiCN film on its surface that has not undergone free radical treatment into the processing container 1 of the substrate processing apparatus 100, and performing the free radical treatment in step S2 of the aforementioned substrate processing method within the processing container 1. The conditions for the free radical treatment were the same as those for the free radical treatment in the first experiment.

[0088] Next, the film formed on the surface of the prepared substrate was analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Figure 5 This is a graph showing the surface analysis results of the SiO2 film that has not undergone free radical treatment.

[0089] Figure 6 This is a graph showing the surface analysis results of the SiCN film that has not undergone free radical treatment. Figure 7 This is a graph showing the surface analysis results of a SiCN film that has undergone free radical treatment. Figure 5 to Figure 7 In the figure, the horizontal axis represents the SiO2 equivalent depth [nm] from the film surface, and the vertical axis represents the secondary ion intensity [count].

[0090] like Figure 5 As shown, secondary ion intensity originating from Si2O5 was detected in the SiO2 film that was not subjected to free radical treatment.

[0091] like Figure 6 and Figure 7 As shown, the SiCN film treated with free radicals exhibits higher secondary ion strengths originating from Si₂O₅, Si₂NO₂, and Si₃NO₅ components compared to the SiCN film without free radical treatment. The increase in secondary ion strength from Si₂O₅, Si₂NO₂, and Si₃NO₅ components is particularly significant in the range of 0 nm to 2 nm from the surface of the SiCN film. Based on these results, it is believed that by applying free radical treatment to the SiCN film, an oxide layer is formed on the surface of the SiCN film. In particular, since Si₂O₅ is a component contained in SiO₂ films, it is considered that by applying free radical treatment to the SiCN film, the surface of the SiCN film becomes similar to that of a SiO₂ film.

[0092] (Third Experiment)

[0093] First, a substrate with a SiCN film on its surface was prepared. Next, the prepared substrate was placed into the processing container 1 of the substrate processing apparatus 100, and the free radical treatment of step S2 of the aforementioned substrate processing method was performed within the processing container 1. In step S2, the free radical treatment time, RF power, and the concentration of oxygen contained in the first processing gas were varied. The conditions for the free radical treatment were as follows.

[0094] (Free radical treatment)

[0095] Substrate temperature: 65℃

[0096] Time: 0 minutes, 10 minutes, 30 minutes

[0097] RF power: disconnect, connect

[0098] The oxygen concentration in the first processed gas was 75.8% and 20.4%.

[0099] Next, the oxygen concentration on the surface of the SiCN film treated with free radicals was determined by X-ray photoelectron spectroscopy (XPS).

[0100] Figure 8 This is a graph showing the oxygen concentration on the surface of the SiCN film. Figure 8 In the graph, the leftmost bar represents the oxygen concentration on the surface of the SiCN film without free radical treatment. The second bar from the left represents the oxygen concentration on the surface of the SiCN film after free radical treatment for 10 minutes, with RF power off and the oxygen concentration of the first processing gas at 75.8%. The third bar from the left represents the oxygen concentration on the surface of the SiCN film after free radical treatment for 10 minutes, with RF power on and the oxygen concentration of the first processing gas at 75.8%. The fourth bar from the left represents the oxygen concentration on the surface of the SiCN film after free radical treatment for 30 minutes, with RF power on and the oxygen concentration of the first processing gas at 75.8%. The fifth bar from the left represents the oxygen concentration on the surface of the SiCN film after free radical treatment for 10 minutes, with RF power on and the oxygen concentration of the first processing gas at 20.4%. The sixth bar from the left represents the oxygen concentration on the surface of the SiCN film subjected to free radical treatment under the conditions of 30 minutes, RF power on, and an oxygen concentration of 20.4% in the first processing gas. Figure 8In this context, the oxygen concentration of the surface layer of a SiCN film that has undergone free radical treatment and one that has not is represented by a relative value when the oxygen concentration of the surface layer of the SiCN film that has not been treated with free radicals is set to 1.

[0101] like Figure 8 As shown, the oxygen concentration on the surface of the SiCN film treated with free radicals was higher than that on the surface of the SiCN film treated without free radicals. Based on this result, it is believed that the free radical treatment has a greater effect on the oxidation of the SiCN film surface than the non-free radical treatment.

[0102] like Figure 8 As shown, the oxygen concentration of the SiCN film treated with free radicals for 30 minutes was higher than that of the SiCN film treated with free radicals for 10 minutes. Based on this result, it is believed that the surface oxidation of the SiCN film can be enhanced by increasing the free radical treatment time.

[0103] like Figure 8 As shown, the oxygen concentration on the surface of the SiCN film is higher when the oxygen concentration in the first processing gas during the free radical treatment is 75.8% than when the oxygen concentration in the first processing gas during the free radical treatment is 20.4%. Based on this result, it is believed that the oxidation of the SiCN film surface can be enhanced by increasing the oxygen concentration in the first processing gas during the free radical treatment.

[0104] (Experiment 4)

[0105] First, a substrate with a SiCN film on its surface was prepared. Next, the prepared substrate was placed into the processing container 1 of the substrate processing apparatus 100, and steps S2 to S9 of the aforementioned substrate processing method were performed within the processing container 1. In step S6, the number of times for the first treatment was set to 3. In step S2, the free radical treatment time, RF power, and the concentration of oxygen contained in the first processing gas were varied. The conditions for the free radical treatment (step S2) were as follows. The conditions for the COR treatment (step S4) and heat treatment (step S8) were the same as those for the COR treatment and heat treatment in the first experiment.

[0106] (Free radical treatment)

[0107] Substrate temperature: 65℃

[0108] Time: 10 minutes

[0109] RF power: disconnect, connect

[0110] The oxygen concentration in the first processed gas was 75.8% and 20.4%.

[0111] Next, the etching amount of the SiCN film was measured. Figure 9 This is a graph showing the etching amount of the SiCN film. Figure 9 In the graph, the leftmost bar represents the etching amount [nm] of the SiCN film without free radical treatment. The second bar from the left represents the etching amount [nm] of the SiCN film treated without free radicals under the conditions of 10 minutes, RF power off, and an oxygen concentration of 75.8% in the first processing gas. The third bar from the left represents the etching amount [nm] of the SiCN film treated with free radicals under the conditions of 10 minutes, RF power on, and an oxygen concentration of 75.8% in the first processing gas. The fourth bar from the left represents the etching amount [nm] of the SiCN film treated with free radicals under the conditions of 10 minutes, RF power on, and an oxygen concentration of 20.4% in the first processing gas.

[0112] like Figure 9 As shown, the etching amount of the SiCN film treated with free radicals was greater than that of the SiCN film without free radical treatment and the SiCN film treated without free radicals. Based on this result, it is demonstrated that by performing free radical treatment before COR treatment, the etching amount of the SiCN film is increased.

[0113] like Figure 9 As shown, the etching amount of the SiCN film is greater when the oxygen concentration of the first processing gas in the free radical treatment is 75.8% than when the oxygen concentration of the first processing gas in the free radical treatment is 20.4%. Based on this result, it is shown that increasing the oxygen concentration in the first processing gas in the free radical treatment increases the etching amount of the SiCN film.

[0114] Furthermore, based on the results of the third and fourth experiments, it is believed that increasing the oxygen concentration of the oxide layer formed on the surface of the SiCN film before COR treatment is effective in increasing the etching amount of the SiCN film.

[0115] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The above embodiments may also be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0116] In the above embodiments, the substrate processing apparatus is described as a batch processing apparatus that processes multiple substrates simultaneously, but this disclosure is not limited thereto. For example, the substrate processing apparatus may also be a single-sheet processing apparatus that processes substrates one by one.

[0117] Explanation of reference numerals in the attached figures

[0118] 1: Processing container; 20: Gas supply unit; 90: Control unit; 100: Substrate processing apparatus.

Claims

1. A substrate processing method, comprising: Step (a): Prepare a substrate with a nitride film on its surface; Step (b) involves exposing the substrate to a plasma generated from a first processing gas containing hydrogen and oxygen; Step (c) involves supplying the substrate with a second processing gas comprising a fluorine-containing gas and an alkaline gas; Step (d) involves performing steps (b) and (c) for the first time in the order of steps (b) and (c); and Step (e) is performed after step (d) by heat treatment of the substrate.

2. The substrate processing method according to claim 1, wherein, The step (b) includes oxidizing the surface of the nitride film to form an oxide layer.

3. The substrate processing method according to claim 2, wherein, Step (c) includes modifying the oxide layer into a reaction product. The step (e) includes removing the reaction product by sublimation.

4. The substrate processing method according to any one of claims 1 to 3, wherein, The process (b) includes maintaining the temperature of the substrate at a first temperature. The process (c) includes maintaining the temperature of the substrate at a second temperature. The second temperature is the same as the first temperature.

5. The substrate processing method according to claim 4, wherein, The process (e) includes maintaining the temperature of the substrate at a third temperature. The third temperature is a temperature higher than the second temperature.

6. The substrate processing method according to any one of claims 1 to 3, wherein, The processes (c) and (e) are performed within the same processing container.

7. The substrate processing method according to any one of claims 1 to 3, wherein, The nitride film is a SiN film, a SiCN film, or a BN film.

8. A substrate processing apparatus comprising: Handling containers; A gas supply unit supplies processing gas to the processing container; and Control Department in, The control unit causes the following processes to be performed: Step (a): Prepare a substrate with a nitride film on its surface; Step (b) involves exposing the substrate to a plasma generated from a first processing gas containing hydrogen and oxygen; Step (c) involves supplying the substrate with a second processing gas comprising a fluorine-containing gas and an alkaline gas; Step (d) involves performing steps (b) and (c) for the first time in the order of steps (b) and (c); and Step (e) is performed after step (d) by heat treatment of the substrate.

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